The Department of Justice is set to make the formal announcement of charges tomorrow against hackers with ties to Russia investigators believe were behind a breach of information regarding hundreds of millions of Yahoo accounts, according to a law enforcement source.
The law enforcement source would not say if the breach was connected to the Russian government itself.
Hackers stole data that included names, email addresses and passwords -- but not financial information, according to Yahoo's announcement regarding the breaches. Sources familiar with the case say the indictment has been under seal.
The DOJ and San Francisco FBI office have both scheduled press conferences for tomorrow on undisclosed topics.
Yahoo has been breached at least twice, and the company previously said a September 2014 breach was state-sponsored, but declined to identify who it believed was responsible.
The announcement of another cyber intrusion by Russian hackers comes at a time of delicate relations between the US and Russia.
The Yahoo hack would be the latest cyberattack that US authorities have blamed on Russia, a nation which President Donald Trump's new administration has sought to foster warmer relations with. Previous attacks US authorities have said Russian hackers perpetrated exposed the emails of Hillary Clinton's campaign chairman, John Podesta, and the internal workings of the Democratic National Committee.